diff options
Diffstat (limited to 'drivers/tty/tty_ldisc.c')
| -rw-r--r-- | drivers/tty/tty_ldisc.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index fc4c97cae01e..45eda69b150c 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -327,6 +327,11 @@ int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) { int ret; + /* Kindly asking blocked readers to release the read side */ + set_bit(TTY_LDISC_CHANGING, &tty->flags); + wake_up_interruptible_all(&tty->read_wait); + wake_up_interruptible_all(&tty->write_wait); + ret = __tty_ldisc_lock(tty, timeout); if (!ret) return -EBUSY; @@ -337,6 +342,8 @@ int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) void tty_ldisc_unlock(struct tty_struct *tty) { clear_bit(TTY_LDISC_HALTED, &tty->flags); + /* Can be cleared here - ldisc_unlock will wake up writers firstly */ + clear_bit(TTY_LDISC_CHANGING, &tty->flags); __tty_ldisc_unlock(tty); } @@ -471,6 +478,7 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld) static void tty_ldisc_close(struct tty_struct *tty, struct tty_ldisc *ld) { + lockdep_assert_held_exclusive(&tty->ldisc_sem); WARN_ON(!test_bit(TTY_LDISC_OPEN, &tty->flags)); clear_bit(TTY_LDISC_OPEN, &tty->flags); if (ld->ops->close) @@ -492,6 +500,7 @@ static int tty_ldisc_failto(struct tty_struct *tty, int ld) struct tty_ldisc *disc = tty_ldisc_get(tty, ld); int r; + lockdep_assert_held_exclusive(&tty->ldisc_sem); if (IS_ERR(disc)) return PTR_ERR(disc); tty->ldisc = disc; @@ -615,6 +624,7 @@ EXPORT_SYMBOL_GPL(tty_set_ldisc); */ static void tty_ldisc_kill(struct tty_struct *tty) { + lockdep_assert_held_exclusive(&tty->ldisc_sem); if (!tty->ldisc) return; /* @@ -662,6 +672,7 @@ int tty_ldisc_reinit(struct tty_struct *tty, int disc) struct tty_ldisc *ld; int retval; + lockdep_assert_held_exclusive(&tty->ldisc_sem); ld = tty_ldisc_get(tty, disc); if (IS_ERR(ld)) { BUG_ON(disc == N_TTY); @@ -760,6 +771,10 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) return retval; if (o_tty) { + /* + * Called without o_tty->ldisc_sem held, as o_tty has been + * just allocated and no one has a reference to it. + */ retval = tty_ldisc_open(o_tty, o_tty->ldisc); if (retval) { tty_ldisc_close(tty, tty->ldisc); @@ -825,6 +840,7 @@ int tty_ldisc_init(struct tty_struct *tty) */ void tty_ldisc_deinit(struct tty_struct *tty) { + /* no ldisc_sem, tty is being destroyed */ if (tty->ldisc) tty_ldisc_put(tty->ldisc); tty->ldisc = NULL; |